1. Field of the Invention
The invention relates to a water-jet drive with a stator and a rotor enclosed by a housing having an inlet and an outlet jet or nozzle in which the rotor shaft supporting the rotor is rotatably supported by shaft bearings arranged upstream and downstream.
2. Background of the Related Art
As is well-known, water-jet drives as well as known screw drives are produced as complete drive units, procured by shipbuilding yards, and connected with the finished boat hulls. For this purpose, suitable openings must be arranged in the lower stern or transom. When using jet drives, the base of the boat must also be constructed in such a way that space is allowed for the inlet duct.
For this purpose, as is shown e.g. in DE 21 52 308, the shaft bearing located upstream penetrates the wall of the boat to be connected with the jet drive, which wall forms part of the inlet duct, whereas the downstream shaft bearing is arranged in a hub of the part of the stator housing downstream of the rotor, the jet drive being formed by the stator.
According to FR 1 335 579, the jet drive is constructed in such a way that the inlet duct lies outside the hull of the boat so that openings for the shaft of the drive unit are only provided in the transom of the hull.
In order to allow shipbuilders also to perform such assembly work in a technically accurate and inexpensive manner, it is required that the drive unit be constructed in such a way that it can be connected with the ship hull in a simple and secure fashion so that required adjusting processes, particularly with respect to the driven rotor shaft, can be carried out in a reproducible manner at any time without great technical expense. This also applies particularly to boat hulls which are constructed as inflatable boats, since in this instance such jet drives are also assembled by persons lacking technical training.
As is well known, water-jet drives have a so-called pump with a stator and a rotor for accelerating and expelling the water required to produce propulsion. In such drives an exact adjustment of the gap between the conical housing or stator and the rotor is required so as to minimize so-called gap losses. The opposite defining surfaces of the housing or stator and rotor blades can be cylindrical and/or conical. Further, after longer operation of such pumps it is advantageous that the adjustment between the stator and rotor, also with respect to the housing, can be readjusted.
This adjustment or readjustment was formerly effected by means of spacer washers, e.g. between a stop on the rotor shaft and the rotor slid onto the rotor shaft so that the rotor to be driven could be adjusted relative to the housing and to the stationary stator. After inserting these spacer washers, the rotor shaft supported between two pivot bearings in the pump housing was defined in these pivot bearings in a fixed manner with respect to its axial adjustment.
An adjustment of the rotor relative to the conical housing by means of spacer washers is costly and difficult and requires specialized knowledge. In particular, time and labor must be expended for the above-mentioned readjustment of the rotor shaft, since the pump housing with the jet control arranged thereon must be extensively disassembled.